A Typical Fuel Train or High Pressure Gas Train has several components, each with a specific purpose which is briefly explained below: Manual shut-off valve (MSOV) – the purpose of this valve is to shut off the fuel supply so that maintenance or replacement of the fuel train may be done. Gas pressure regulator (PRV) – its purpose is to maintain the fuel at a constant pressure as recommended by the burner manufacturer. Gas Filter – the function is to prevent foreign particle and extraneous impurities entering Gas Pressure Regulator. Low pressure gas switch – senses a low pressure in the range where the burner cannot properly operate. This switch must be equipped with safety lock-out requiring manual reset. This tells the operator to check the gas pressure, since the burner will not try to restart until the switch is reset. Safety shut-off valve (SSOV) – the first of two valves in series that automatically opens and shuts off the fuel supply to the burner...